Equipment and method for mounting electronic components

ABSTRACT

The cycle time for mounting electronic components supplied from a tray can be shortened. An electronic component feeder ( 16 ) for mounting electronic components has a plurality of height levels (L 1 , L 2 , and L 3 ) and can move tables ( 19, 20, 21 ) horizontally at the respective levels (L 1 , L 2 , and L 3 ). A plurality of conveyers ( 22, 23, 24 ) are provided for the respective tables to move them to a pickup stage (A) from a standby stage (B). Transfer head ( 13 ) includes nozzles ( 14   a,    14   b,    14   c ) for attracting electronic components by suction, and an upward-downward moving mechanism which moves the nozzles in accordance with the height level of each tray on the pickup stage (A). Since the trays are arranged at the different height levels at the pickup stage position, the conveyers can be moved independently and the transfer heads can individually move the nozzles between the position at which each nozzle picks up electronic components and another position at which the nozzle does not interfere with the pickup operation. Movement of a necessary tray from and to the pick up stage position can be performed quickly without being hindered by an other tray and, as a result, the cycle time for mounting electronic components can be shortened.

FIELD OF THE INVENTION

The present invention relates to mounting electronic components usingmore than one nozzle provided on a transfer head for picking upelectronic components placed on more than one vertically-staged tray,and transferring and mounting them onto a substrate.

BACKGROUND OF THE INVENTION

At present, a common type of electronic component mounting equipmentpicks up a selection of electronic components supplied via an electroniccomponent feeder by vacuum suction of a transfer head nozzle andtransfers and mounts them onto a substrate. There are various types offeeders which supply electronic components to the nozzle of the transferhead, and one type employs a tray.

An electronic component feeder of the prior art which employs this trayis explained next.

FIG. 13 shows a side view of an electronic component feeder of the priorart. In FIG. 13, a magazine 1 houses a tray 2 which stores more than oneelectronic component aligned lengthwise and crosswise in verticalmultiple stages. A certain in/out level 3 is specified in theconventional electronic component feeder, and the magazine 1 is raisedor lowered by elevation means 4 to move the tray 2 to this in/out level3 for moving the tray 2 to a subsequent pickup stage 6 next. In/outmeans 5 is for ejecting the tray 2 at the in/out level 3 from themagazine 1 to the pickup stage 6, or to return the tray 2 on the pickupstage 6 to the magazine 1.

When the tray 2 required to be on the pickup stage 6 (refer to the tray2 represented by a dotted line) is ejected, a nozzle 8 of a transferhead 7 lowers toward the tray 2, and an electronic component P on thetray 2 is picked up by suction at the tip of the nozzle 8. Theelectronic component P, shown by a dotted line, is then transferred andmounted onto a substrate 9, for example, a printed circuit board.

With the above electronic component feeder of the prior art, however, along time is required to replace the tray 2 positioned on the pickupstage 6, resulting in a longer feeding cycle time, which in turn lowersproductivity. The reasons are as follows. For replacing the tray 2 shownby the dotted line in FIG. 13 with the tray 2 x in the magazine 1, thefollowing series of operations cannot be avoided:

(1) the in/out means 5 returns the tray 2 from the pickup up stage 6 tothe magazine 1;

(2) the elevation means 4 raises the magazine 1 to set the tray 2 x tothe in/out level 3; and

(3) the in/out means 5 ejects the tray 2 x set to the in/out level 3 tothe pickup stage 6.

SUMMARY OF THE INVENTION

The present invention provides a method and equipment for mountingelectronic components which enables the shortening of feeding cycletime, and which also allows the high speed transfer and mounting ofelectronic components onto a substrate.

The electronic component mounting equipment of the present inventioncomprises a positioning unit for positioning a substrate, an electroniccomponent feeder for supplying electronic components, and a transferhead which moves between the electronic component feeder and thepositioning unit for transferring and mounting supplied electroniccomponents onto a positioned substrate. The abovementioned electroniccomponent feeder comprises tray holders for holding a tray storing morethan one electronic component, a frame support having more than onevertical stage for the tray holders so as to move each tray holderhorizontally at each height level, and more than one in/out means movingmechanism disposed for the tray holders for transferring each trayholder from a standby stage to a pickup stage. The abovementionedtransfer head comprises a nozzle for suctioning electronic componentsand a vertical movement mechanism for moving the nozzle in accordancewith a height of each tray on the pickup stage.

The electronic component mounting method of the present invention is tomove electronic components stored on a tray to the pickup stage, pick upan electronic component using the nozzle of the transfer head, and mountit on the substrate. In this method, more than one level for ejectingand returning the tray to and from the pickup stage is provided with acertain interval in the vertical direction. The tray is ejected at eachlevel for positioning the tray on the pickup stage, and the electroniccomponent on the tray is then picked up with the nozzle to be mounted onthe substrate.

The electronic component mounting method of the present inventionfurther picks up electronic components on the trays set at more than onevertical level of the pickup stage with more than one vacuum suctionnozzle provided on the transfer head, and transfers and mounts theelectronic component onto a substrate positioned with the positioningunit. The transfer head is moved over the trays disposed on theplurality of vertical stages, and electronic components are picked up inorder from the upper tray to the lower tray by moving more than onenozzle vertically in order. When one nozzle is lowered for picking up anelectronic component, other nozzles which do not pick up electroniccomponents also lower together.

The electronic component mounting equipment as configured above operatesas follows.

Each tray can be independently ejected to and returned from the pickupstage at different levels. The nozzle of the transfer head also movesvertically in response to the level of the tray positioned on the pickupstage by the vertical movement mechanism. This allows prompt setting upof the required tray at the pickup stage as required for picking up theelectronic component with the nozzle to immediately mount it on thesubstrate. In other words, the present invention enables the saving oftime required for elevating the magazine and ejecting or returning thetray after elevation, which is unavoidable with the electronic componentmounting equipment of the prior art. Accordingly, the mounting cycletime can be reduced.

Moreover, by providing more than one level with a certain interval inthe vertical axis for ejecting or returning the tray at each level toand from the pickup stage, the ejection or returning operation of arequired tray can be promptly executed without interfering with othertrays, also resulting in a reduction of the mounting cycle time.Furthermore, by disposing the transfer head over the trays disposed inmore than one vertical stage, electronic components are picked up inorder from the upper to the lower trays by the vertical movement of morethan one nozzle. Those nozzles which do not pick up electroniccomponents also lower together with the nozzle which lowers to pick upelectronic components. This allows the reduction of the cycle timerequired for picking up electronic components on the tray by moving thenozzle vertically and the cycle time required for moving the nozzle overthe substrate and then moving vertically again to mount the electroniccomponent on the substrate. Thus, electronic components on the tray canbe mounted on the substrate at high speed with good operability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of electronic component mounting equipment inaccordance with an exemplary embodiment of the present invention.

FIG. 2 is a perspective of a part of the electronic component mountingequipment of the present invention.

FIG. 3 is a section view of the electronic component mounting equipmentof the present invention.

FIG. 4 is a perspective of a transfer head of the electronic componentmounting equipment of the present invention.

FIGS. 5A-5D explain a first example of processes of an electroniccomponent mounting method of the present invention.

FIGS. 6A-6C explain a second example of processes of the electroniccomponent mounting method of the present invention.

FIGS. 7, 8, 9, 10, 11, and 12 explain a third example of processes ofthe electronic component mounting method of the present invention.

FIG. 13 is a side view of an electronic component feeder of the priorart.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An exemplary embodiment of the present invention is explained withreference to drawings.

One exemplary embodiment of electronic component mounting equipment ofthe present invention is explained with reference to FIGS. 1 to 4. InFIG. 1, arrows X, Y, and Z indicate directions. A conveyor 11 isprovided over a long distance in the X direction on a top face of a base10 for transporting a substrate 12 and functioning as a substratepositioning unit for positioning the substrate 12 at a specifiedposition. A transfer head 13 comprises more than one nozzle, for pickingup electronic components with vacuum suction at their tips. The transferhead 13 is horizontally movable in X and Y directions on the base 10 byan X table 19A and a Y table 19B. An electronic component monitoringunit 40 is disposed at the side of the conveyor 11. A transfer directionof the substrate 12 by the conveyor 11 is the X direction.

An electronic component feeder 16 is for supplying electroniccomponents. A frame 17 of the electronic component feeder 16 is fixed tothe base 10. The electronic component feeder 16 is disposed with a sidetoward the conveyor 11, and comprises a pickup stage A, which is an areafor picking up an electronic component by suction with a nozzle of thetransfer head 13, a standby stage B at the center, and a refill stage Cwhich is disposed at the opposite side of the pickup stage A forrefilling electronic components by replacing an empty tray with anothertray. A cover 18 is provided over the standby stage B. A parts feeder 15is for supplying electronic components which are not provided in trays(e.g. a tape feeder and a tube feeder).

An outline of the internal structure of the electronic component feeder16 is explained with reference to FIG. 2. As shown in FIG. 2, theelectronic component feeder 16 of the exemplary embodiment of thepresent invention has three tables, which are a first table 19, a secondtable 20, and a third table 21 from the bottom. The first table 19 isconnected to a first conveyor 22, the second table 20 to a secondconveyor 23, and the third table 21 to a third conveyor 24. The firstconveyor 22 is driven independently by a first motor 25, the secondconveyor 23 by a second motor 26, and the third conveyor 24 by a thirdmotor 27. Accordingly, the first table 19, second table 20, and thirdtable 21 can be independently taken in and out in the direction shown byarrows N1, N2, and N3. The first table 19, second table 20, and thirdtable 21 are equivalent to a tray holder for holding the tray, and thefirst conveyor 22, second conveyor 23, and third conveyor 24 areequivalent to the in/out means.

Detailed structure of the electronic component feeder 16 of theexemplary embodiment of the present invention is explained withreference to FIG. 3. As shown in FIG. 3, a first stage 17 a, secondstage 17 b, and third stage 17 c are provided on the upper part of theframe 17, and they are stepped downward from the center to the outside.A slider S fixed to the bottom face of the first table 19 is fitted inslidable fashion to the first guide 28 fixed to the first stage 17 a. Inthe same way, the second table 20 and the third table 21 are supportedin slidable fashion respectively by the second guide 29 fixed to thesecond stage 17 b and the third guide 30 fixed to the third stage 17 c.A first tray 31 stores the first electronic component 32 and is placedon the first table 19, a second tray 33 stores the second electroniccomponent 34 and is placed on the second table 20, and a third tray 35stores the third electronic component 36 and is placed on the thirdtable 21. Here, in each tray placed on each table, the first tray 31 ispositioned at the first level L1, which is the bottom stage, the secondtray 33 is positioned at the second level L2, which is the middle stage,and the third tray 35 is positioned at the third level L3, which is thetop stage. The level L0 is a monitoring level for electronic components(to be explained later).

The side of the second table 20 is bent vertically downward at theoutside of the first table 19, and then bent perpendicularly towards theframe 17 at the bottom of the first table 19, reaching the slider S. Inother words, the side of the second table 20 detours around the firsttable 19 and bends towards the center of the frame so that the structureof the electronic component feeder 16 can be made more compact byminimizing the width of the second table 20. With the same intention,the side of the third table 21 is designed to detour around the secondtable 20, and is bent towards the center of the frame 17 to reach theslider S.

Next, the structure of the transfer head 13 and a monitoring unit 40 isexplained with reference to FIG. 4. The transfer head 13 comprises afirst nozzle 14 a, second nozzle 14 b, and third nozzle 14 c which movevertically and independently from each other. As explained later, theypick up the first electronic component 32, second electronic component34, and third electronic component 36, respectively, by suction, andtransfer and mount them on the substrate 12.

The first nozzle 14 a, second nozzle 14 b, and third nozzle 14 c havethe same vertical movement mechanism. These nozzles comprise a headframe 51, a feeding screw 52 which is vertically held by the head frame51, a z-axis motor 53 which is mounted onto the upper part of the headframe 51 for rotating the feeding screw 52, a nut 54 which is hinged tothe feeding screw 52, and moves vertically when the feeding screw 52 isrotated, a nozzle shaft 55 vertically provided on the nut 54, and around back plate 56 attached to the nozzle shaft 55. The nozzle shaft 55rotates by an angle θ when driven by a head motor 57 and a belt 58.Accordingly, when the z-axis motor 53 rotates clockwise orcounterclockwise, the nut 54 moves upward or downward along the feedingscrew 52, and the first nozzle 14 a, second nozzle 14 b, and thirdnozzle 14 c move upward or downward. When the head motor 57 rotates, thenozzle shaft 55 rotates by angle θ for correcting the horizontalrotation angle of the electronic component picked up by suction at thetip of the first nozzle 14 a, second nozzle 14 b, and third nozzle 14 c.

The monitoring unit 40 is configured to house a line sensor 42 inside abox 41. The longer side of the line sensor 42 is provided along the Yaxis, and a slit 43 is opened corresponding to the line sensor 42 at theupper face of the box 41. The transfer head 13 moves perpendicularly(along the X axis) to the direction of the line sensor 42 (y axis) overthe slit 43. The first nozzle 14 a, second nozzle 14 b, and third nozzle14 c are arranged in a line along the X axis. Accordingly, the firstelectronic component 32, second electronic component 34, and thirdelectronic component 36, picked up by suction at the tip of each nozzle,traverse the line sensor 42 as the transfer head 13 linearly moves alongthe X axis. This enables continuous high speed monitoring of theseelectronic components to detect any deviation in the x, y, and θdirections.

Next, a first example of an electronic component mounting method in theexemplary embodiment of the present invention is explained.

FIGS. 5A-5D explain processes of a first example of the electroniccomponent mounting method. As shown in FIG. 5A, the first tray 31,second tray 33, and third tray 35 are placed on the standby stage B.Next, in FIG.5B, the first tray 31, second tray 33, and third tray 35are moved to the pickup stage A at once before the transfer head 13reaches the pickup stage A. Then, at the third level L3, the firstnozzle 14 a picks up the third electronic component 36 from the thirdtray 35 on the top stage.

After completing the pickup operation at the third level L3, the thirdtray 35 immediately returns to the standby stage B as shown in FIG. 5C.After the third tray 35 returns, the second nozzle 14 b immediatelypicks up the second electronic component 34 from the second tray 33 atthe second level L2, and mounts it on the substrate 12. Here, thepresent invention saves the time spent for elevating the magazine orejecting the next tray to the pickup stage A as required with theelectronic component mounting equipment of the prior art, enabling areduction of the electronic component mounting time.

After completing the pickup operation for the second tray 33, the secondtray 33 is immediately returned to the standby stage B as shown in FIG.5D. The first electronic component 32 on the first tray 31 positioned atthe first level L1 is then picked up. When the second tray 33 at thestandby stage B becomes empty, the second tray 33 is moved to the refillstage C (shown by a chain line), and the tray is refilled by replacingit with a new tray full of second electronic components 34. Theelectronic components 36, 34, and 32 can be mounted onto the substrate12 after picking up all of them.

Next, a second example of the electronic component mounting method inthe exemplary embodiment of the present invention is explained.

FIGS. 6A-6C explain processes of the second example of the electroniccomponent mounting method. In this example, trays are not required to bereturned to the standby stage B as in the first example explained above.The trays can be switched with only a small returning operation.Specifically, the first tray 31, second tray 33, and third tray 35 arefirst aligned as show in FIG. 6A, and the first nozzle 14 a picks up thethird electronic component 36 from the third tray 35. Next, the thirdtray 35 is returned relative to the first tray 31 and second tray 33over double the length of the alignment pitch of the electroniccomponents, and the transfer head 13 is moved only for the length of theelectronic component alignment pitch for picking up the secondelectronic component 34 from the second tray 33 with the second nozzle14 b. As shown in FIG. 6C, the second tray 33 is returned over the samedistance as the third tray 35 so that only the first tray 31 protrudesfrom the second tray 33 and the third tray 35. The first electroniccomponent 32 is then picked up from the first tray 31 with the thirdnozzle 14 c.

Then, the transfer head 13 is moved over the substrate 12, and the thirdelectronic component 36, second electronic component 34, and firstelectronic component 32 that have been picked up are mounted onto thesubstrate 12. In this way, the stroke for returning the second tray 33and third tray 35 can be minimized to the degree required to avoidinterfering with pickup of the first electronic component 32 from thefirst tray 31 on the lowest stage, enabling a shortening of the timerequired for mounting electronic components.

A third example of the electronic component mounting method in theexemplary embodiment of the present invention is explained next.

FIGS. 7 to 12 explain processes of the third example of the electroniccomponent mounting method, showing the sequence of operations.Specifically, as shown in FIG. 7, the first tray 31, second tray 33, andthird tray 35 are taken out from the standby stage B to the pickup stageA. Here, the first level L1 of the first tray 31 on the lowest stage iscompletely leveled or approximately leveled to the monitoring level L0for electronic components and the upper face level of the substrate 12(electronic component mounting level). The reason is explained later.

As shown in FIG. 7, the transfer head 13 is moved over the pickup stageA. At first, the first nozzle 14 a, second nozzle 14 b, and third nozzle14 c are set to the highest level, and only the third nozzle 14 c isfirst lowered and raised to pick up the third electronic component 36 inthe third tray 35 at the top stage by suction.

Next, as shown in FIG. 8, the third tray 35 returns to the standby stageB, to expose the second tray 33. The second nozzle 14 b is then loweredor raised to pick up the second electronic component 34 as shown in FIG.9. At this point, the first nozzle 14 a and third nozzle 14 c, which donot pick up electronic components, are also lowered for the stroke H1following the lowering operation of the second nozzle 14 b.

Next, as shown in FIG. 10, the second tray 33 is returned to the standbystage B to expose the first tray 31. The first nozzle 14 a is lowered orraised to pick up the first electronic component 32. Here, the secondnozzle 14 b and third nozzle 14 c which have already picked upelectronic components also lower for the stroke H2 following thelowering operation of the first nozzle 14 a.

As explained above, after the third nozzle 14 c, second nozzle 14 b, andfirst nozzle 14 a respectively pick up the third electronic component36, second electronic component 34, and first electronic component 32 inorder, the transfer head 13 moves over the monitoring unit 40 as shownin FIG. 11 for checking any deviation in the position of the thirdelectronic component 36, second electronic component 34, and firstelectronic component 32 (also refer to FIG. 4).

In this case, all the electronic components 36, 34, and 32 arepositioned at the monitoring level L0 of the monitoring unit 40 bydriving the z-axis motor 53 to lower the first nozzle 14 a, secondnozzle 14 b, and third nozzle 14 c. When picking up the last componentas shown in FIG. 10, not only the first nozzle 14 a which picks up thefirst electronic component 32, but also the second nozzle 14 b and thirdnozzle 14 c which have already picked up the second electronic component34 and third electronic component 36, and not picked up electroniccomponents in the process shown in FIG. 10, are already lowered togetherwith the first nozzle 14 a. Accordingly, the lowering stroke H3 forlowering the third electronic component 36, second electronic component34, and first electronic component 32 from the first level L1 to themonitoring level L0 can be made very short. Thus, the three electroniccomponents 36, 34, and 32 can be continuously monitored at high speed ina well arranged manner for detecting positional deviations in the x, y,and θ directions. It is apparent that this lowering stroke H3 can be setat 0 by setting the monitoring unit 40 at a somewhat higher level.

As shown in FIG. 12, the transfer head 13 then moves over the substrate12, and the third nozzle 14 c, second nozzle 14 b, and first nozzle 14 alower or rise separately to mount the three electronic components 36,34, and 32 one by one at specified coordinates on the substrate 12. Alsoin this case, since the first nozzle 14 a, second nozzle 14 b, and thirdnozzle 14 c are already lowered to the monitoring level L0, the lowlevel, as shown in FIG. 11, the lowering stroke H4 for mounting theelectronic components 36, 34, and 32 can be shortened, enablinghigh-speed mounting. Deviation in the X and Y directions detected by themonitoring unit 40 is corrected by adjusting the movement stroke of thetransfer head 13 relative to the X axis and Y axis of the substrate 12.Deviation in the θ direction is corrected by rotating the nozzle shaft55 by driving the head motor 57 shown in FIG. 4.

The electronic component mounting equipment of the present inventionenables ejection and return of each tray independently to and from thepickup stage at different levels. The nozzle of the transfer head canalso be moved vertically in response to the level of each traypositioned on the pickup stage by the vertical movement mechanism sothat the required tray can be quickly positioned at the pickup stage atthe required time for immediately picking up an electronic componentwith the nozzle for mounting it on the substrate. In other words, thepresent invention saves the time required for elevating the magazine andtaking in and out the tray after elevation, which was unavoidable withthe conventional electronic component mounting equipment, thusshortening the mounting cycle time.

The electronic component mounting method of the present inventionenables the ejection and return of a required tray promptly withoutinterfering with other trays by providing more than one level with acertain interval in the vertical direction for ejecting and returningtrays to and from the pickup stage. As a result, the mounting cycle timecan be shortened.

Moreover, the electronic component mounting method of the presentinvention positions the transfer head over the trays disposed at morethan one vertical level to pick up electronic components from in orderof upper tray to lower tray by moving more than one nozzle vertically inorder. In addition, the nozzles which do not pick up electroniccomponents follow the lowering operation of the nozzle which picks up anelectronic component so that the cycle time required for picking up anelectronic component from the tray by vertically moving the nozzles andthe cycle time required for moving the nozzles over the substrate andmoving the nozzles vertically again to mount electronic components ontothe substrate can be greatly shortened. Accordingly, the presentinvention allows the mounting of electronic components in trays onto thesubstrate at high speed and with good operability.

We claim:
 1. Electronic component mounting equipment comprising: apositioning unit for positioning a substrate; an electronic componentfeeding device for supplying electronic components, said electronicfeeding device comprising: a plurality of tray holders at differentheight levels for holding trays storing electronic components, a supporthaving a plurality of vertical stages supporting said tray holders suchthat each of said tray holders is horizontally movable at theirrespective height levels, and a moving mechanism disposed with said trayholders for horizontally moving each of said tray holders independentlyat their respective height levels between a standby stage and a pickupstage; and a transfer head movable between said electronic componentfeeding device and said positioning unit for transferring and mountingsupplied electronic components onto the positioned substrate, saidtransfer head comprising: a nozzle for picking up said electroniccomponents by suction, and a vertical movement mechanism for verticallymoving said nozzle to the height level of one of the trays on the pickupstage.
 2. A method for mounting electronic components by moving traysstoring electronic components to a pickup stage and picking up theelectronic components with a nozzle of a transfer head to mount saidelectronic components onto a substrate, comprising: setting a pluralityof stage levels with a certain vertical interval for ejecting andreturning the trays to and from the pickup stage; positioning the traysat the pickup stage by ejecting the tray at each stage level; andpicking up the electronic components housed in the trays with the nozzleto mount the electronic components onto said substrate.
 3. A method formounting electronic components by moving electronic components housed intrays disposed in a plurality of vertical stages to a pickup stage,picking up the electronic components with suction with a plurality ofnozzles provided on a transfer head, and transferring and mounting theelectronic components onto a substrate positioned with a positioningunit, comprising: moving the transfer head over the trays disposed inthe plurality of vertical stages; and vertically moving said pluralityof nozzles in sequence to pick up the electronic components from thetrays in order from an upper tray to a lower tray, wherein the nozzleswhich do not pick up the electronic components follow along with alowering operation of the nozzle which picks up the electroniccomponent.
 4. The electronic component mounting equipment of claim 1,further comprising a monitoring unit provided below said transfer head.